Fire detection systems have been recognized as being useful and valuable in commercial buildings in providing an early alarm in the event of a developing fire. From the point of view of responding to a fire condition and potentially evacuating some or all of the associated building, the earliest possible detection of the fire condition is preferred.
Counterbalancing the need for early detection, is a need to minimize or eliminate, if possible, the existence of false or nuisance alarms. Such alarms occur as a result of electrical or other types of environmental noise present in buildings wherein the alarm systems are installed.
Detectors are known which detect not only a potential fire condition, but also detect non-fire environmental conditions. Such known detectors adjust an alarm threshold in response to the presence or the absence of a detected environmental condition.
Environmental conditions of interest include the presence or absence of human beings in the region under surveillance, the condition of machinery in the region under surveillance, along with the time of day. Other conditions of interest include humidity as well as pollution levels in the ambient atmosphere.
Thus, there continues to be a need for multiple sensor detection devices which take into account both ambient conditions such as potential or actual fires along with other environmental conditions. Preferably, such devices could be manufactured at a cost comparable to known devices.